<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title></title>
    <style>
      /*
        原理：两个元素设置浮动，右侧自适应元素宽度使用calc函数计算
        缺点：父元素需要清除浮动
      */
      * {
        padding: 0;
        margin: 0;
      }
      .box {
        height: 600px;
        width: 100%;
      }
      .left {
        float: left;
        width: 100px;
        height: 200px;
        background-color: red;
      }
      .right {
        float: left;
        width: calc(100% - 100px);
        height: 400px;
        background-color: blue;
      }
    </style>
  </head>
  <body>
    <div class="box">
      <div class="left">
        <span> 123adadadddddddddddddddddddddddddddddddddddddddd </span>
      </div>
      <div class="right"></div>
    </div>
  </body>
</html>
